Co-crystals are a homogeneous multicomponent system including at least one drug substance (i.e., active ingredient) and at least one co-former, which are held together by supramolecular synthons. Pharmaceutical co-crystals have attracted significant interest due to the co-crystals' contribution to potential advantageous physicochemical properties of the drug substance, for example, improved solubility, dissolution rate, bioavailability, physical and/or chemical stability, flowability, hygroscopicity, processability, etc. Furthermore, minimizing the hygroscopicity of drug substance can be one of the most challenging tasks in drug development and manufacturing.
In co-crystal development, suitable co-formers for making pharmaceutical co-crystals of a particular drug substance are typically identified by approaches based on trial and error. Thus, the selection of suitable co-formers for a drug substance and the ratio between the drug substance and the co-former to produce desirable pharmaceutical co-crystals, as well as methods for making such, are the main challenges for producing pharmaceutical co-crystals for a particular drug substance.